unistd.h is a C/C++ header files contains needed to provide access to the POSIX operating systems
Links:
https://en.wikipedia.org/wiki/Unistd.h
https://pubs.opengroup.org/onlinepubs/009695399/basedefs/unistd.h.html
Questions tagged [unistd.h]
175 questions
217
votes
10 answers
Is there a replacement for unistd.h for Windows (Visual C)?
I'm porting a relatively simple console program written for Unix to the Windows platform (Visual C++ 8.0). All the source files include "unistd.h", which doesn't exist. Removing it, I get complaints about misssing prototypes for 'srandom',…
AShelly
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41
votes
3 answers
Cannot open include file: 'unistd.h': No such file or directory
After having installed libpng into my computer, I've included it into my project using #include on a Windows 7 SP1 plateform and using Visual Studio Ultimate 2013.
But at build time, I'm getting this error:
C1083: Cannot open include file:…
user3471387
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30
votes
2 answers
How to call execl() in C with the proper arguments?
i have vlc (program to reproduce videos)
if i type in a shell:
/home/vlc "/home/my movies/the movie i want to see.mkv"
it opens up an reproduces the movie.
however, when I run the following program:
#include
int main(void) {
…
Matias Morant
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14
votes
3 answers
clang++: fatal error: 'unistd.h' file not found
Using OS X 10.10.2, I download Clang for Mac OS X v. 3.6.0, and try to compile a simple Hello World program.
The commands I use are these:
(assumes you downloaded clang to .)
cd .
./clang+llvm-3.6.0-x86_64-apple-darwin/bin/clang++ main.cpp
The…
user4664340
13
votes
2 answers
What is the difference between fsync and syncfs?
What is the difference between fsync and syncfs ?
int syncfs(int fd);
int fsync(int fd);
The manpage for fync says the following :
fsync() transfers ("flushes") all modified in-core data of (i.e., modified buffer cache pages
for) the…
cominfotty
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13
votes
4 answers
C sleep function not working
When including the sleep function from unistd.h the program hangs indefinitely:
#include
#include
int main()
{
int i;
printf("0 ");
for(i = 1; i <20; ++i)
{
sleep(2);
…
James Jenkinson
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12
votes
3 answers
Fast input/output in competitive programming
I have come across this particular snippet of code many times in solutions of competitive programming contests. I understand the basic use of this code to beat time limits but i want to understand it more deeply. I know that unistd.h gives access to…
s2n
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8
votes
1 answer
Difference between unistd.h and sys/types.h in linux
When I have searched for the header unistd.h, in The Open Group, I found that it contains the standard symbolic constants & types and for sys/types.h it said for data types.
Then I found that both have uid_t, pid_t and several similar types.
I am…
user3511557
7
votes
3 answers
redirecting standard output in c then resetting standard output
I'm trying to use redirects in C to redirect input to one file and then set standard output back to print to the screen. Could someone tell me what's wrong with this code?
#include
#include
#include
int main(int argc,…
David
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7
votes
1 answer
execl crashes C++ node.js-addon
As normal C++ execl works fine (compiling with g++ ok.cc -o ok.elf)
#include
int main(){
execl("/usr/bin/python", "/usr/bin/python", nullptr);
}
But crashes, when works as node.js C++ addon
#include
#include…
Евгений Новиков
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- 7
7
votes
1 answer
Attempting to use execvpe(...) but get implicit declaration error - even though I think I'm using the correct argument types
I am getting the following warning when I compile:
execute.c:20:2: warning: implicit declaration of function ‘execvpe’[-Wimplicit-function-declaration] execvpe("ls", args, envp);
^
My understanding is that this occurs when the function you are…
newbie
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6
votes
4 answers
unistd's execl() without passing any arguments
In my code I need to execute /bin/bash, but I wan't to do it without passing any arguments to it. I wrote this:
execl("/bin/bash", NULL);
Then, through some research, I realized that I also need to add type cast:
execl("bin/bash", (char*)…
Błażej Michalik
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5
votes
2 answers
Race condition during file write
Suppose two different processes open the same file independently, and so have different entries in the Open file table (system-wide). But they refer to the same i-node entry.
As the file descriptors refer to the different entries in the Open file…
arka
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5
votes
3 answers
What does #define __REDIRECT_NTH do in unistd.h?
GNU unistd.h has this bit of magic:
/* Move FD's file position to OFFSET bytes from the
beginning of the file (if WHENCE is SEEK_SET),
the current position (if WHENCE is SEEK_CUR),
or the end of the file (if WHENCE is SEEK_END).
Return…
vy32
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5
votes
1 answer
What does libc_hidden_proto in the glibc standard libraries do?
I was trying to look up the prototype for the getpgrp() function in unistd.h but couldnt find it. The only line containing getpgrp in that file was the line libc_hidden_proto (tcgetpgrp) and I'm assuming this is a macro, but I dont know what it…
Jerry Marbas
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